Buffer method for well fluid balance in downhole operation and multifunctional buffer fluid flow valve

Abstract

The invention discloses a downhole operation well fluid balance buffering method and a multifunctional buffering fluid valve applicable to multiple processes of oilfield downhole operation field construction. According to the downhole operation well fluid balance buffering method, one buffering fluid valve is connected to the upper portion of a drift size gauge tool or other downhole operation tool in a downhole operation string, speed of well fluid entering the inside of an oil pipe in the process of lowering of the down-hole string is effectively controlled, fluid level in the oil pipe is allowed to be lower than that in a casing, pressure in the oil pipe is enabled to be basically kept in balance with the pressure in the casing, and the well fluid is prevented from spattering from the oil pipe to the ground. The fluid valve comprises a working barrel connected with a pressing cap, and a bidirectional fluid control device is mounted in the working barrel. The fluid levels in a shaft can be kept in balance, the oil pipe is prevented from injection and overflow in the lowering process of the oil pipe string, cleanliness and sanitation are realized, and operation is facilitated. Meanwhile, requirements on conventional and inverse well flushing are met, slurry is ensured to be displaced completely, an oil layer is protected against secondary damage, and technical problems perplexing production for a long time are solved.

Description

technical field [0001] The invention relates to a method and a tool for downhole operations in the petroleum industry, in particular to a buffer method for well fluid balance in downhole operations and a multifunctional buffer fluid flow valve, which are suitable for multiple processes in the field construction of downhole operations in oil fields, especially for the construction of new wells and the construction of old wells. Well sand flushing, drilling plugs, casing scraping, falling object fishing, etc. can balance the liquid level in the wellbore, prevent the tubing from spraying liquid, and meet the requirements of positive and reverse well washing. Background technique [0002] When oil production wells in the petroleum industry are operating downhole, they often encounter the situation that the tubing and casing return liquid at the same time during the process of running the tubing string. It can be sprayed on the wellhead without control. When the well fluid is oi...

AI Technical Summary

Problems solved by technology

Strictly speaking, this is a violation of regulations, because the inner cavity of the running string is empty, but the casing is full, which will cause an excessive pressure difference between the oil jacket annulus and the inner cavity of the oil pipe, causing damage to the oil pipe. Great damage. In severe cases, the oil pipe may be deformed, resulting in a fee for the oil pipe, which not only increases the production cost, but also leads to rework of the process, delays the production schedule, and increases the workload of the workers.

In addition, the pipe string with a check valve at the bottom can only be flushed, and cannot be used for backwashing

For the construction of mud replacement, it can only be replaced by positive replacement, so that the mud in the wellbore cannot be replaced, and the mud will enter the formation after perforation, causing secondary pollution and seriously affecting the production of the oil well.

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